The following decision matrix compares several methods of shaping plastic bottles into prosthetic parts. We decided to test each of the methods in lab because the resulting values were all relatively close.
Shaping Theoretical Decision Matrix:
Weight
25
5
20
15
15
20
100%
Shaping Method
Cost/
Availability
Time
Skill/
Training
Equipment/
Tooling
Shape
Versatility
Consistency/
Repeatability
Total
Heat Gun/Blow Dryer
2
5
3
2
5
4
3.2
Boiling Water
4
2
4
4
2
5
3.8
Fired Oven
3
2
3
3
2
3
2.8
Propane Torch
2
5
2
2
5
4
3
Open Flame
5
3
5
5
3
1
2.55
After testing, it was clear that boiling water, a propane torch and an open flame were the best shaping methods. Heating with a blow dryer did not work at all, and an open flame worked much better than expected
Shaping Test Results Matrix:
Weight
25
5
20
15
15
20
100%
Shaping Method
Cost/
Availability
Time
Skill/
Training
Equipment/ Tooling
Shape
Versatility
Consistency/
Repeatability
Total
Boiling Water
4
3
5
4
2
5
4.05
Propane Torch
2
5
2
2
5
2
2.6
Open Flame
5
3
4
5
3
3
4
It was concluded that Boiling water or an open flame were both viable options.
Then arose the debate of how to effectively attach an extension that would not only deliver an added functionality, but serve as an extension of the amputee him/herself.
---New Decision Matrices to go here---
Bottle Forming Methods
Propane Torch
The torch method method did not produce uniformly spread heat.
Open Flame
An open flame caused the bottle to shrink more uniformly and didn't require additional equipment or propane.
Mold Casting Methods: Current Approach used by the Center for International Rehabilitation
Mold Casting Methods: Appropriate Technology Approach
The following decision matrix shows data from testing methods of producing a negative of an arm. Plaster will be poured into the negative to form a positive that the bottle will be shaped around. Wax molding scored highest, because of the high accuracy molds, reusable wax and fast drying time. Wax is expensive, but because it is reusable and a versatile material it's long run cost is less than clay, which is not reusable.
Molding Test Results Matrix:
Category Weight
20
10
30
10
10
80
Molding Method
Cost
Set Time
Shape Accuracy/ Repeatability
Training
Equipment and Tooling
Total
Wax Negative
10
10
34
8
8
70
Clay Negative
7
5
15
9
10
46
Paper Mache Negative
20
1
3
10
10
44
Wax + Plaster Casting
A wax mold was made from Aaron's thumb.
The mold was filled plaster of paris, creating a positive of Aaron's thumb.
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Design Process
The following decision matrix compares several methods of shaping plastic bottles into prosthetic parts. We decided to test each of the methods in lab because the resulting values were all relatively close.
Shaping Theoretical Decision Matrix:
Availability
Training
Tooling
Versatility
Repeatability
Oven
Shaping Test Results Matrix:
Availability
Training
Tooling
Versatility
Repeatability
Then arose the debate of how to effectively attach an extension that would not only deliver an added functionality, but serve as an extension of the amputee him/herself.
---New Decision Matrices to go here---
Bottle Forming Methods
Propane Torch
Open Flame
Mold Casting Methods: Current Approach used by the Center for International Rehabilitation
Mold Casting Methods: Appropriate Technology Approach
The following decision matrix shows data from testing methods of producing a negative of an arm. Plaster will be poured into the negative to form a positive that the bottle will be shaped around. Wax molding scored highest, because of the high accuracy molds, reusable wax and fast drying time. Wax is expensive, but because it is reusable and a versatile material it's long run cost is less than clay, which is not reusable.
Molding Test Results Matrix:
Wax + Plaster Casting
Paper Mache
Plaster Casting in the Paper Mache Negative
Plaster Caste After Drying and a Plastic Mold